1. Field of the Invention
The present invention involves a method of operating a direct injection spark-ignited engine (DISE) using a fuel composition comprising a liquid fuel and a fuel additive composition. The method provides for the cleanliness of the fuel system of the DISE.
2. Description of the Related Art
The direct injection spark-ignited engine is a new technology that has been commercially introduced in Japan and Europe by manufacturers Mitsubishi, Nissan and Toyota. The DISE offers significant performance benefits relative to a conventional port fuel injection gasoline engine (PFIGE). The specific power output of a DISE relative to a PFIGE is increased, which results in better fuel economy and driveability in terms of throttle response and acceleration. The DISE, when coupled with current catalyst systems for reducing exhaust emissions, also meets exhaust emission standards. The overall performance of a DISE is directly related to the cleanliness of the fuel system. Consequently, methods that provide for the cleanliness of the fuel system of a DISE are very desirable and useful.
International publication WO 00/20537, Haji et al., published Apr. 13, 2000, discloses a gasoline additive comprising at least one nitrogenous compound selected from a nitrogen-containing ether compound and a polybutenylamine compound. The gasoline additive is suitable for use in a gasoline composition for direct injection gasoline engines.
International publication WO 01/42399, Aradi et al., published Jun. 14, 2001, discloses that deposits in a direct injection gasoline engine are reduced by fueling the engine with a fuel composition comprising a Mannich detergent.
A number of technical presentations involve studies done on direct injection gasoline or spark ignition engines that generically disclose nitrogen-containing compounds and polyether fluidizers as fuel additives in these engines:
1. “A Comparison of Gasoline Direct Injection and Port Fuel Injection Vehicles, Part 1: Fuel System Deposits,” Arters et al., 5th Annual Fuels & Lubes Asia Conference, 1999;
2. “A Comparison of Fuel System Deposits and Lubricant Performance in Gasoline Direct Injection and Port Fuel Injection Vehicles,” Macduff et al., 2nd International Fuels Colloquium, Jan. 20-21, 1999;
3. “A Comparison of Gasoline Direct Injection and Port Fuel Injection Vehicles; Part 1—Fuel System Deposits and Vehicle Performance,” Arters et al., SAE Paper No. 1999-01-1498 presented at International Spring Fuels and Lubricants Meeting and Exposition, May 3-6, 1999;
4. “A Study of Fuel Additives for Direct Injection Gasoline (DIG) Injector Deposit Control,” Aradi et al., SAE, Spec. Publ., VSP-1551, Diesel and Gasoline Performance and Additives, p 283-293;
5. “Deposit Formation and Control in Direct Injection Spark Ignition Engines,” Ohkubo et al., 6th Annual Fuels & Lubes Asia Conference, Jan. 25-28, 2000;
6. “The Effect on Vehicle Performance of Injector Deposits in a Direct Injection Gasoline Engine,” Arters et al., SAE Paper No. 2000-01-2021.
Japanese Patent Publication JP 11-35952, Nippon Oil Company, published Feb. 9, 1999, discloses an alcoholic compound as a gasoline additive for in-cylinder direct injection type gasoline engines.
The method of the present invention effectively provides for the cleanliness of a fuel system of a DISE by operating the engine with a fuel composition comprising a liquid fuel and a fuel additive composition. The present invention controls deposits in fuel injectors and combustion chambers of a DISE that contributes to vehicle performance in the areas of fuel economy, driveability and exhaust emissions.